This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The objective of this research protocol is to continue my thirty year investigation of the nature and prevalence of mitochondrial disease. The mitochondria are organelles within the cytoplasm of our cells that produce most of the energy necessary for cellular function. The mitochondrial are in fact semi-autonomous bacteria living within our cells. These bacteria interred the progenitors of our cells as symbionts about three billion years ago, before multi-cellular plants and animals evolved. Today these mitochondria are an integral part of our cells without which we could not live.